Susha (Dragon Ball GT: A Hero's Legacy) attempts to swallow Goku Jr. whole.
The Eds' (Ed Edd n Eddy) jaws are literally fit for eating jawbreakers the size of their heads.
Horrors (New Blood Interactive's DUSK) have stretchable jaws that reach right down to their body, and can also come in useful when devouring flesh, and also tend to use it any time they shoot out the acid from within their bodies.
Indominus rex (Jurassic World)
Red (NES Godzilla Creepypasta) swallowing Melissa's entire body while chasing Godzilla.
Monkey D. Luffy (One Piece) using Gum-Gum Munch-Munch/Gomu Gomu no Baku Baku.
Pig God (One Punch Man)
A Leviathan (Supernatural) opening its mouth to "eat".